First degree rape—Penalties.

No person convicted of rape in the first degree shall be granted a deferred or suspended sentence except for the purpose of commitment to an inpatient treatment facility: PROVIDED, That every person convicted of rape in the first degree shall be confined for a minimum of three years: PROVIDED FURTHER, That the *board of prison terms and paroles shall have authority to set a period of confinement greater than three years but shall never reduce the minimum three-year period of confinement; nor shall the board release the convicted person during the first three years of confinement as a result of any type of good time calculation; nor shall the department of corrections permit the convicted person to participate in any work release program or furlough program during the first three years of confinement. This section applies only to offenses committed prior to July 1, 1984.